Automatic calling appliance for telephone trunk-lines.



No. 645,572. Patented Mar. 20. I900.

c. E. SGRIBNER.

AUTOMATIC CALLING APPLIANCE FUR TELEPHONE TRUNK LINES.

(Application filed Mar. 9, 1898.)

(No Model.)

m a W Witnesses:

UNITED STATES PATENT GFEICE,

CHARLES E. SORIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, on SAME PLACE.

AUTOMATIC CALLING APPLIANCE FOR TELEPHONE TRUNK-LINES.

SPECIFICATION forming part of Letters Patent No. 645,572, dated March20, 1906.

Application filed March 9 1 8 9 8- To all whom it may concern.-

Be it known that I, CHARLEs E. SCRIBNER,

a citizen of the United States, residing at Ohicago, in the county ofCook and State of Illinois, have invented a certain new and usefulImprovement in Automatic Calling Appliances for Telephone Trunk-Lines,(Case No. 461,) of which the following is a full, clear, concise, andexact description.

This invention applies to incoming trunklines for use in makingconnection with telephone-lines provided with means for altering theresistance of the line-circuit in the use of the telephone. The purposeof the invention is to provide simplified apparatus and circuits forapplying and removing the operators telephone or other testingappliance, for

applying and withdrawing a source of callingcurrent, for ringing'thebell at the station to be called, and for controlling the display of asignal-lamp associated with the trunk-line in the switchboard.

In many exchanges of modern equipment the circuit of each line is soarranged at the substation thereof that the line is normally open, butbecomes closed through the agency of the telephone-switch while thereceiving telephone is in use. With such lines supervisory signals areemployed in the telephoneswitchboard to indicate the closed or opencondition of the line circuit, whereby the attendant may infer thecondition of use or disuse of the line and may perform any necessaryacts of supervision or disconnection. The mechanism of the supervisorysignal commonly comprises a source of current in the line, a relay inthe line responsive to current therein while the telephone is in use,and a signal-lamp in a local circuit controlled by the relay, thesignal-lamp being associated with the connecting-plug or link-conductorby means of which connection is established between different lines. Thelink-conductor may of course be either a trunk-line between differentexchanges terminating as an incoming trunk-line in a switchboard of therelay type here referred to or a pair of plugs with their plug-circuitwithin the switchboard; but inasmuch as the advantages of automaticringing are more pronounced when the ring- I ing mechanism is applied totrunk-lines 1 Serial No. 673.206. (No model.)

shall describe my invention in connection with the apparatus andoperation of trunklines. It will be understood that the same apparatusmay be used in connection with plug-circuits complete Within a singleswitchboard.

In a relay-switchboard, such as that herein described, the functions ofthe attendant having Charge of incoming trunk-lines consist in receivingorders for connections, test ing the lines called for, making therequired connections, transmitting calling currents to the stationscalled for, and removing the connections in accordance with the displayof the supervisory signals.

The present invention provides for the automatic connection anddisconnection of the operators telephone for testing, the automaticconnection of the source of callingcurrent and its disconnection whenthe called party responds to the signal, and the extinction of thesupervisory signal until such response. To this end it comprises a groupof switch-springs adapted normally to break'the circuit of thetrunk-line and to connect the operators telephone or other testinginstrument with the testing-contact of the terminal plug, anelectromagnet adapted, when excited, to disconnect the telephone and toap- 8o ply the source of calling current to the terminal plug, and meansfor exciting the magnet in making connection with the line,-the'supervisory relay, a second electromagnet,

means for controlling the same through the I agency'of the supervisoryrelay, the second magnet being adapted to deprive the first mentionedmagnet of current, and to close the break in the trunk-line, means formaintaining the continued excitement of the second-mentioned'magnet whenit has been operated, a local circuit including the supervisorysignal-lamp, and means for breaking the circuit while the source ofcalling current is applied to the line. The specific construc- 9 5 tionof this apparatus and arrangement of the circuits for these purposes areshown in the attached drawing. This drawing represents a telephonelineterminating in the usual connecting apparatus of a telephoneswitchboard,together with the incoming ter-' minal of a trunk-line or otherlink-conductor line and the line of a calling subscriber.

designed to make connection from another line, whether in the same or ina different exchange, to the line shown in the drawing.

The apparatus at the substation comprises the usual telephones a and a,a polarized call-bell (1. a condenser a permanently in circuit with thebell, and a telephone-switch a for closing the normally-- open circuitthrough the telephones when the switch is relieved from the weight ofthe receiving telephone. From these appliances line conductors l and 2extend to the terminal contacts of spring-jacks b in atelephone-switchboard, from which theyare normally prolonged through theswitch-contacts of a cutotf relay 0 to the poles of a battery e, commonto the different lines of the exchange, the magnet-winding of a relay (Zbeing interposed in the conductor 2, controlling a secondaryline-signalf, associated with one of the springjacks.

The trunk-line comprises conductors 3 and 4, which. are brought intoelectrical connection with the line-contacts of the terminal plug 9 ofthe trunk-line in the switchboard. The trunk-line conductors 3 and 4 maylead to any suitable apparatus at a different exchange or in the sameswitchboard, whereby connection may be made between the trunk- Thewindings of a repeating coil h are interposed in the trunk-line, nearthe incoming end thereof, in the usual way, two of the four windingsbeing serially connected in each conductor of the trunk-circuit,-and asource 2' of current is connected in a bridge 5 of the trunk-circuitbetween the points of junction of the serially-connected windings. Thissource of current is for the purpose of operating the signals belongingto the trunk-line and of supplying current for the excitement of thetransmitting telephone at a substation with which the trunk-line isconnected. The usual supervisory relay 7a is also included in anextension of conductor 3 of the trunkline controlling a supervisorysignal It, which is associated with the terminal plug 9 in theswitchboard. The means by which the signal is controlled by the relaymust be described in connection with the call-sending mechanism.

The mechanism which forms the subject of this invention consists in twoelectromagnetic switches Z and on, with their circuits. The appliance Zconsists of a magnet Z and two switch-springs l Z each with a normal andan alternate resting-anvil, the anvils ot the different springs beingdenoted by the letters 1 Z and Z Z respectively. The magnet Z should beof comparatively-high resistance, one hundred ohms being suitable. Theother appliance m comprises an electromagnet m, provided withswitch-springs m and m each having normal and. alternate contacts m mand m 011 respectively. The magnet m has two windings m and m". Theformer of these should be of comparatively-low resistance, thirteen ohmsbeing a proper amount, while the latter should have a resistance as highas fifty ohms. The switch-springs Z and Z form the terminals of wires 6and '7, which lead to the sleeve and tip contacts, respectively, of theterminal plug 9 of the trunk-line. These conductors are thus in effectextensions of the trunk-line 3 4 when the line is in use. The normalrestin g-contact l of spring l is connected by wire 8 with theswitch-spring m The resting-contact Z of spring Z is connected directlywith conductor 3 of the trunk-line. The alternate contact Z of spring Zis connected by a wire 9 to earth. The corresponding contact Z of thespring Z leads to one pole of a grounded generator at of calling currentof usual form. The resting-contact m of lever m? constitutes theterminal of a wire lO, leading to the operators telephone and groundedtherethrough. The alternate contact m of the same spring forms theterminal of line conductor 4 of the trunlcline. Switch-spring m isconnected with the terminal of abattery 0. This battery may have anelectromotive force of twenty volts. The normal resting-contact of thesame spring forms the terminal of a wire 11, leading to themagnet-winding of magnet Z. The alternate contact an of the same springis connected by wire 12 with one extremity ofwinding m of relay m, whoseother terminal is led by wire 13 to lamp 7c, the other terminal of thislamp being connected, through wire 14, with a third contact-piece g thiscontactpiece being adapted to register in the usual way with acontact-ring in the spring-jack b, which forms the terminal of a portion15 of a local circuit, including the magnet-winding of the cut-off relay0 of a line into which the plug is inserted. The free terminal of magnetZ is connected with this wire 14:. Also one switch-contact of thesupervisory relay 7c is connected by wire 17 with conductor 14. Theother contact-piece of the same relay is united by wire 16 with windingm of magnet 172" The supervisory signal It may be a ten-volt lamp. Theresistance of magnet 0 may be eighty-five ohms.

While all the apparatus is in its inert condition the conductor 3 of thetrunk-line is in electrical connection with the sleeve of theconnecting-plug by way of conductor 6. The connection of the tip of theplug with the conductort of the trunlcline is severed, however, thecircuit being closed by way of conductors 7, 8, and 10 to the operatorstelephone.

Assume that the incoming trunk operator listening at this telephonereceives an order to connect the trunk-line 3 t with a subscribers lineterminating in the switchboard. Her first act is to raise the plug 9 andtest the line called for by applying the tip of the plug to thetest-ring b of a spring-jack of the line. In correspondence withordinary practice the existence of a connection with any springjack of asubscribers line will have altered the electrical condition of thesetest-rings by applying a source of current to the rings to raise them toa difference of potential from earth. Hence at each application of thetesting-plug to the test-ring current will flow from the ring throughconductors 7, 8, and 10. Each pulsation of current will produce a clickin the operators telephone. In case no connec tion exists with the linetested no such sounds will be heard. It will be noted that inasmuch asno connection exists between conductor 7 and the remaining portion ofwire 4 of the trunk-line no disturbance can arise in the operatorstelephone on account of foreign electromotive forces in the trunk-line.Having found the line free, the operator inserts plug g into thespring-jack tested. This act brings the conductors 6 and 7 intoconnection with line-wires 2 and 1 of the telephone-line. At the sametime it permits current to flow from battery 0 through wires 11, 14, and15. This current excites the cut-off relay 0 of the line with whichconnection has been made,causing this appliance to sever the normalground connections of the line, while at the same time it electrifiesthe test-rings b to make the line test busy to subsequent attempts toconnect with it. Magnet Z also becomes excited,whereby the wire 7 isbroken from wire 8 and closed to wire 9 and wire 6 is severed from wire3 of the trunk-line and is connected with the calling generator at, thesprings Z and Z having been raised from their resting-anvils and thrustagainst their alternate anvils. Calling current from the source 'n thenflows out over the circuit 6v 2 1 7 9, which rings the bell a at thesubstation of the line. WVhen in response to the call the user of thetelephone removes the receivingtelephone from its switch and permits theswitch to close the line-circuit through the telephones, the current inthe circuit becomes greatly increased, the resistance of the condenserand the bell having been cut out. Thus the supervisory relay becomesexcited and, attracting its armature, closes the circuit 16 17,including the winding m of magnet m. This magnet being thus excitedwithdraws its switchsprings m m from their normal contact-anvils andthrusts them against their alternate anvils m and m respectively,whereby the circuits are altered as follows: The connection of wire 11with battery 0 is. broken, the magnet l is deprived of current, thesprings 1 F are permitted to fall against their normal resting-anvils Z1 respectively, and thus the conductor 3 of the trunk-line is extendedby way of wire 6 to the sleeve-conductor of the terminal plug g.Connection is established between wires 8 and 4 at the point-of contactof spring m and anvil m so that conductor 7, terminating in the tip ofplug g, is made a continuation of conductor-4 of the trunk-circuit. Wire10 is disconnected from wire 8, and thus becomes wholly severed from thetalking circuits of the trunk-line, the op erators telephone being thusfinally disconnected from the circuit. A local circuit is &

formed from battery 0 through wires 12, 13,

14, and 15, which includes the signal-lamp 10, together with winding mof magnet m, and inasmuch as this circuit is independent of the actionof supervisory relay 70 the magnet m will remain continuously excitedwhile connection exists between wires 14 and 15. A shunt exists,however, about the lamp 76' in wires 17 and 16, whereby the extinctcondition of this lamp is maintained while the relay k is excited. Thusafter making the test of the line the operators insertion of the pluginto the spring-jack tested disconnects her telephone from thetrunk-line and applies the source of calling current to the line of thestation to be signaled. The response of the called party effects thedisconnection of the calling current and brings about the operativeconnection of the trunk-line withthe terminal plug, whereby thesubscribers line is brought into circuit with the line con nected withthe distant end of the tru nk-line. The supervisory signal remains inertwhile the source of calling current is applied to the line, but isbrought under the control of the called party after his response to thecall, after which it serves to indicate his signal for disconnection.

In many cases the display of signal It to indicate that the telephone atthe called station has been replaced on its switch may be followed bythe disconnection of the trunk-line usual way without interfering withthe mechanism of the present invention.

The invention is defined in the following claims:

1. The combination with telephone-lines having call bells at theirsubstations and switches for changing the resistance of the lines, and aterminal plug of a trunk-circuit for making connection with a line, ofan electromagnet controlling a break in the trunkcircuit, said breakbeing closed when the electromagnet is inert, a switch-spring actuatedby the magnet adapted to connect a contactpiece of the terminal plugwith a source of calling current, a second clectromagnet responsive tocurrent in the line produced by the operation of the switch at thestation thereof, a local circuit and means for closing the same in theact of making connection with the line by means of said plug, themagnetwinding of said first'meutioned magnet being included in saidlocal circuit, and switch-contacts of said second-mentionedelectromagnet controlling the continuity of the local circuit;

If, however, it is desired to whereby said first-mentioned magnetapplies calling current to a telephone-line with which connection ismade, but is deprived of current and closes the break in theplug-circuit when the telephone at the called station is taken for use,as described.

2. The combination with telephone-lines, call-bells connected therewith,and switches at the stations thereof operated in the use of thetelephones for diminishing the resistance in the line-circuit, of atrunk-line and the terminal plug thereof for making connection with anyline, a calling appliance consisting of a magnet and a switch-springactuated thereby normally closing a break in the trunkcircuit, andadapted, when actuated, to open the said break and connect a source ofcalling current with the terminal plug, a second electromagnetcontrolled by current through the subscribers line when increased by thediminution of the line resistance, a local circuit including the magnetof said calling appliance closed in registering contact-pieces of theplug and the spring-jack of a line, and switch-contacts of said secondmentioned electromagnet normally completing said local circuit butadapted to break it when the magnet is excited, a local circuit for saidsecondmentioned electromagnet, and switchcontacts actuated by theelectromagnet to close the local circuit thereof; whereby the trunklineis interrupted and calling current is applied to a line when connectionis made therewith, but the source of calling current is disconnected inthe use of the telephone at the substation and remains disconnectedthereafter during the use of the line, as described.

3. The combination with telephone-lines, each provided with a call-bellat its station and with a switch and means controlled thereby forchanging the resistance of the line in the use of the telephone, withspring-jacks for making connection with the line, of a trunkline and aterminal plug thereof, a magnetically-controlled calling switch and amagnetically controlled telephone switch, switchcontacts of thetelephone-switch forming a normal break of the trunk-circuit andconnecting the testing-contact of the terminal plug with the operatorstelephone or testing appliance, switch-contacts of the calling appliancenormally completing the conductor leading to said testing-contact butadapted, when the magnet is excited, to break such normal connection andapply one pole of a source of calling current to said contact; a localcircuit including the electromagnet of said calling appliance andregistering contacts of the plug and spring-jack adapted to complete thesaid local circuit, auxiliary switch-contacts of the telephone-switchadapted to break the circuit through the magnet of said callingappliance when the magnet of the telephone-switch is excited; means forexciting the magnet of the telephone-switch in response to increase ofcurrent in the line-circuit with which the plug is connected, a localcircuit including a winding of the magnet of the telephone-switch,together with switchcontacts of the said switch closed when the magnetis excited, and means for breaking the said local circuit when the plugis withdrawn from the spring-jack, substantially as described.

4. The combination with a telephone-line having a high-resistancecall-bell at its station and a switch for cutting out the call-bell inthe use of the telephone, a spring-jack for the line, and alocal-circuit conductor terminating in a contact-piece thereof, atrunk-line, a terminal plug therefor, and a relay in the trunk-circuitadapted to respond to current in the line when the said bell is cut out;of a magnetically-controlled calling switch having switch contactsnormally completing breaks in the dilferent line conductors of thetrunk-circuit, but adapted, when excited, to apply the poles of a sourceof calling current to the conductors leading to said terminal plug, alocal circuit including the magnet of said calling switch, said localcircuit terminatin g in a switch-contact of the plug adapted to makeconnection with the local circuit of a telephone-line to excite themagnet; a magnetically-controlled telephone-switch having aswitch-spring normally forming a break in the conductor of thetrunk-circuit leading to the test-contact of the terminal plug, andconnecting the said test-contact with a telephone or other testingappliance, but adapted to close said break and disconnect the saidtelephone appliance, a branch of the local circuit closed between theplug and spring-jack in cluding the magnet of said telephone-switch,said branch being controlled by the supervisory relay; otherswitch-contacts of said telephone-switch normally completing the circuitthrough the magnet of said calling switch but adapted to break the samewhen the magnet is excited; a local circuit including a winding of themagnet of said telephone-switch, said circuit being a branch of thelocal circuit closed between the plug and spring-jack, andswitch-contacts controlled by the same magnet to complete the saidcircuit when the magnet is excited, substantially as described.

5. The combination with telephone-lines, each having a call-bell at itsstation and a switch for reducing the resistance of the line in the useof the telephone, a spring-jack for the line, a trunk-line and aterminal plug thereof for making connection with the springjack, asupervisory relay in the trunk-line and a supervisory signal associatedwith the terminal plug; of a magnetically-controlled calling switchhaving switch-contacts normally closing the different line conductors ofthe trunk-line, but adapted to break the said I of the circuit includingthe magnet of said calling switch ,a telephone-switch, switch-contactsthereof forming a normal break in the conductor of the trunk-circuitleading to the testing-contact of said plug, and connecting the saidtesting-contact with an operators telephone or other testing appliance,said switch-contacts being adapted to sever the connection with thetelephone and complete the connection with the trunk-circuit when thecontrolling-magnet is excited, a second branch of the said local circuitincluding the controlling-magnet of said telephone-switch, said secondbranch being controlled by the switchcontacts of the supervisory relay;other switch-contacts of the telephone-switch normally closing thebranch of the local circuit through the magnet of the calling switch,but adapted to break the said circuit when the magnet of thetelephone-switch is excited a third branch of the local circuitincluding the supervisory signal, together with a winding of the magnetof the telephone-switch, controlled by switch-contacts of thetelephoneswitch closed when the magnet is excited, said winding being ofcomparatively-low resistance, substantially as described.

6. The combination with trunk-lines and terminal plugs thereof for usein multiple switchboardspf an electromagnetic appliance having acontrolling-magnet in a local circuit closed in registering contacts ofthe plug and spring-jack, switch-contacts of the said appliance normallybreaking the connection of the test-contact of said plug with the remainder of the trunk-circuit and connecting it with the operatorstelephone for testing, substantially as described.

7. The combination with a trunk-line and a terminal plug thereforadapted for connection with multiple spring-jacks of the telephone-line,of calling and switching mechanism for controlling-magnets in a localcircuit closed in registering contacts of the plug and spring-jack, saidmechanism being adapted when inert to disconnect the testing-contact ofthe plug from the remainder of the trunkline and to connect it with aterminal of the operators telephone, and when excited to disconnect theoperators telephone and connect a source of calling current with theterminal plug, substantially as described.

In witness whereof I hereunto subscribe my name this 31st day ofJanuary, A. D. 1898.

CHARLES E. SORIBNER,

Witnesses:

ELLA EDLER, GENEVA STEVENS.

